The subject matter disclosed herein relates generally to providing for cooling of devices mounted to an electric motor and, more specifically, to a system for providing active cooling of a position feedback device mounted to one end of a motor.
Electric motors are commonly used in many applications. Electric motors include a housing in which the rotor and stator are mounted. A motor shaft, coupled to the rotor extends through one end of the housing and is coupled to a device to be driven by the motor. Operation of an electric motor generates heat. The amount of heat is dependent on many factors, such as the magnitude of current applied to the motor, the frequency of rotation of the motor, winding construction, and the like. The motor and housing will be designed to manage and dissipate the heat as effectively as possible. The final construction of the motor will result in certain operating characteristics for the motor. The operating characteristics may define for example, current ratings, torque ratings, temperature ratings, and the like for the motor.
As is understood in the art, it is often desirable to provide a motor drive or other devices, such as a position feedback device to control operation of a motor. The motor drive typically includes solid state switching devices that control the amplitude and frequency of voltage supplied to the motor, which, in turn, controls the speed and/or torque produced by the motor. Position feedback devices are coupled to the rotor of the motor to generate a signal corresponding to the angular position of the rotor. The motor drive may use the position signal directly to cause the motor to move to a desired angular orientation or convert the position signal into a speed signal to, cause the motor to rotate at a desired speed.
In certain environments, it is desirable to provide a housing around the position feedback device, where the housing may be connected to the end of the motor. The housing may prevent contamination from dust or liquid in the atmosphere and/or may protect the position feedback device from being physically struck during assembly, operation, and/or maintenance of the machine on which the motor and feedback device is mounted. It is known, however, that heat may build up within the housing around the position feedback device. In addition, the position feedback device may not be designed to withstand the same environmental conditions as the motor. As a result, the position feedback device and, in particular, an enclosed position feedback device may be the thermally limiting component for a motor assembly. Therefore, the motor in the motor assembly may not be able to operate up to its full temperature rating for which it was designed in, order to avoid damaging the position feedback device.
Thus, it would be desirable to provide a system for cooling an enclosed position feedback device mounted to a motor.